24 ANIMAL CHEMISTRY LECTURE II. 



twenty; whereas, among organic or carbon compounds, bodies 

 containing scores of constituent atoms are very frequently met 

 with, a few of which, by way of illustration, are written up on 

 the table before you. 



Formulae Proximate Organic Principles Atoms 



C 6 H IO 5 Starch 21 



C 6 H I4 6 Mannite 26 



C I3 H I8 7 Salicin 38 



C 20 H M Og Populin 50 



C 27 H a3 I7 Tannin 66 



C z6 R M Cholesterin 71 



C 3a H 64 0^ Spermaceti 98 



C 46 H 9Z 0,5 Myricin 140 



C 57 H JI0 06 Stearin 173 



First of all we have starch, a compound consisting of 6 atoms 

 of carbon, 10 of hydrogen, and 5 of oxygen, making altogether 

 2 1 atoms. Next we have mannite, the crystallisable principle of 

 ordinary manna, of which it forms, I believe, as much as 60 or 

 70 per cent. It contains, as shown by its formula, 6 atoms of 

 carbon, 14 of hydrogen, and 6 of oxygen, making altogether 26 

 atoms. Next we come to the crystallisable bitter principle of 

 willow bark, namely, salicin, which, I am informed by manu- 

 facturers, is still largely produced and used as a substitute for 

 quinine. It is characterised, as you see, by the red colouration 

 it experiences when acted upon by sulphuric acid, and consists, 

 as shown by its formula, of 38 constituent atoms. Next we 

 come to populin, a similar crystallisable principle, less generally 

 known and less widely distributed. It is found in the bark and 

 leaves of the poplar, and contains 50 constituent atoms ; while 

 tannin contains 66 atoms, and cholesterin 71. I may take this 

 opportunity of observing that cholesterin, heretofore regarded as 

 an exclusively animal product, is now known to enjoy an exten- 

 sive distribution in the vegetable kingdom, having been extracted 

 from peas, wheat, almond oil, olive oil, &c. We pass on to 

 spermaceti, with its 98 atoms ; to myricin, or purified beeswax, 

 with its 140 atoms; and, lastly, to stearin, with its 173 atoms of 

 carbon, hydrogen, and oxygen. Comparing tri-elementary bodies 



